LRO finds McGetchin, a 222-metre lunar crater formed in 2024

A rock the size of a three- to six-storey building hit the eastern limb of the Moon sometime between 11 April and 22 May 2024. The hole it left is 222 metres across and 43 metres deep. NASA’s Lunar Reconnaissance Orbiter has now given it a name, McGetchin, after the late planetary scientist Thomas McGetchin, and two papers in Science Advances, posted 16 September, call it the largest newly formed impact crater yet found anywhere in the solar system.

Robert Wagner, an image-processing specialist at Intuitive Machines who works with LRO Camera data, was the person who stopped. He was comparing a wide-angle mosaic from summer 2025 with a map from spring 2011. A bright patch appeared where none had been. “I just stopped, dropped everything, and started looking into what that spot was,” he said. The white mark in the wide-angle frames is not the floor of the crater. It is ejecta. The pit itself sits near the boundary between dark mare and brighter highlands.

What the instruments added

LRO has logged at least 1,000 new craters in more than 17 years on station. Most of them are tens of metres across. The team checks for small changes as a matter of routine. Every few years it builds a global map and looks for scars wider than about 45 metres. McGetchin is several times that threshold.

Tyler Powell, lead author of one of the new papers, told Space.com the luck was in the timing. A crater of this size is expected on the Moon only about once a century. Models cited with the NASA release tighten that to once every 132 years. LRO was flying both before and after the strike, which is the rare condition that turns a hole into a measured event.

The Narrow-Angle Camera imaged the floor on 5 December 2025. Diviner, the orbiter’s thermal instrument, found a cold spot about four miles wide around the crater, roughly 9 degrees Celsius cooler at night than the ground beside it. That halo is the part of the story that reaches beyond the rim. The impact did not only dig a pit. It changed how the surface holds heat over an area far larger than 222 metres.

Why the date range is a window, not a day

LRO does not stare at one patch. The before-and-after pair that brackets McGetchin runs from 11 April to 22 May 2024. No Earth telescope has yet been publicly credited with catching the flash. The object was not tracked on the way in. Its size is inferred from the hole and the ejecta, not from a catalogued asteroid designation.

That matters for models of the near-Earth population. A building-sized fragment that reaches the Moon without a public warning is also a fragment that could have reached Earth. The lunar surface keeps the record. Earth’s atmosphere erases most of it.

What the papers do not claim

They do not claim the object was a comet rather than an asteroid. They do not assign a precise kinetic energy beyond the scale implied by diameter and depth. They do not say the cold spot will last for a geologic age. They do say the crater is a chance to watch a fresh lunar wound while the spacecraft that found it is still working.

Human landers and commercial landers are now a planning fact, not a slogan. A once-a-century strike is still rare. It is not zero. McGetchin is a measured reminder that the surface NASA wants people to use is still being rewritten by rocks that nobody named on the way in.

Wagner’s working habit was to look at maps. The useful fact for everyone else is the size, the date window, the 9-degree night-time cold ring, and the 132-year recurrence the models now quote. Those four numbers did not exist in public until this week.